U.S. patent application number 10/095638 was filed with the patent office on 2003-10-23 for integrally formed heavy media pulping column.
Invention is credited to Placha, Daniel S., Watters, Larry A..
Application Number | 20030197079 10/095638 |
Document ID | / |
Family ID | 29214387 |
Filed Date | 2003-10-23 |
United States Patent
Application |
20030197079 |
Kind Code |
A1 |
Watters, Larry A. ; et
al. |
October 23, 2003 |
Integrally formed heavy media pulping column
Abstract
In a coal preparation plant which receives a raw coal feed and
separates the raw coal feed into a clean coal feed and a refuse
feed, an apparatus is provided for use therein. The inventive
apparatus mixes the sized raw coal feed particles with a slurry of
media and water used for separating the raw coal feed into clean
coal and refuse. The inventive apparatus includes a pulping column
integrally designed with the discharge chute of a deslime screen
and the drain section underpan of clean coal and refuse screens.
The pulping column having a coal inlet receiving the sized raw coal
directly from the deslime screen, a media inlet receiving the
slurry of media and water directly from an underpan of at least one
of the refuse screen and the clean coal screen, and an outlet
discharging the mixture of sized raw coal and slurry. The pulping
column mixes the sized raw coal and the slurry of media and water
according to a select proportion, and it is then pumped to a heavy
media separation section of the coal preparation plant.
Inventors: |
Watters, Larry A.;
(McMurray, PA) ; Placha, Daniel S.; (Oakdale,
PA) |
Correspondence
Address: |
BUCHANAN INGERSOLL, P.C.
ONE OXFORD CENTRE, 301 GRANT STREET
20TH FLOOR
PITTSBURGH
PA
15219
US
|
Family ID: |
29214387 |
Appl. No.: |
10/095638 |
Filed: |
March 12, 2002 |
Current U.S.
Class: |
241/38 |
Current CPC
Class: |
B03B 9/005 20130101;
B03B 13/00 20130101 |
Class at
Publication: |
241/38 |
International
Class: |
B02B 001/00 |
Claims
We claim:
1. In a mineral preparation plant receiving a raw mineral feed and
separating the raw mineral feed into clean mineral and refuse, an
apparatus for mixing the raw mineral feed particles with a slurry
of media and water, said apparatus comprising: a pulping column
having a mineral inlet receiving sized raw mineral directly from a
deslime screen, a media inlet receiving a slurry of media and water
directly from an underpan of at least one of a refuse screen and a
clean mineral screen, and an outlet outputting a mixture of the
sized raw mineral and slurry, wherein the pulping column mixes the
sized raw mineral and the slurry of media and water according to a
select proportion having a select specific gravity.
2. The apparatus of claim 1, wherein the mineral comprises coal,
and wherein the media comprises magnetite.
3. The apparatus of claim 1, wherein the pulping column is
integrally formed with discharge chutework of the deslime screen,
such that the sized raw mineral from the deslime screen feeds
directly to the pulping column.
4. The apparatus of claim 1, wherein the pulping column is
integrally formed with a drain section of the underpan of at least
one refuse screen and the clean mineral screen, such that the
slurry of media and water from the drain section feeds directly to
the pulping column.
5. The apparatus of claim 1, wherein the pulping column is
integrally formed with both discharge chutework of the deslime
screen and a drain section of the underpan of at least one of the
refuse screen and the clean mineral screen, such that the sized raw
mineral from the deslime screen and the slurry of media and water
from the drain section feeds directly to the pulping column for
mixing.
6. The apparatus of claim 1, further comprising a nuclear density
gauge measuring the specific gravity of the mixture output by the
pulping column and a control system, the control system configured
to add water to the output mixture to maintain the output mixture
at the select specific gravity measured by the nuclear density
gauge.
7. The apparatus of claim 6, wherein the control system comprises a
water source connected to the pulping column output via at least
one valve, wherein the control system adjusts the at least one
valve to add water from the water source to the output mixture
based upon the measured specific gravity value as measured by the
nuclear density gauge.
8. The apparatus of claim 7, further comprising a pump for pumping
the pulping column output mixture to a heavy media separating
device, the pump having a suction connected to the pulping column
output and an output connected to an input of the heavy media
separating device, wherein the water source is connected between
the pulping column output and the pump suction, and wherein the
nuclear density gauge is provided between the pump output and the
heavy media separating device input.
9. The apparatus of claim 1, wherein the pulping column is sized
such that no overflow of the sized raw mineral and slurry mixture
occurs.
10. A method of mixing raw mineral feed particles and a slurry of
media and water, said method comprising the steps of: receiving at
a pulping column sized raw mineral directly from a deslime screen;
receiving at the pulping column a slurry of media and water
directly from an underpan of at least one of a refuse screen and a
clean mineral screen; and mixing the sized raw mineral and slurry
in the pulping column according to a select proportion having a
select specific gravity.
11. The method of claim 10, further comprising the steps of:
measuring the specific gravity of the slurry mixture containing the
raw sized mineral; and adding water to the mixture in response to
the measured specific gravity of the mixture to maintain the
mixture at the select specific gravity.
12. The method of claim 11, further comprising the step of:
providing a pump for pumping the sized raw mineral and slurry
mixture from the pulping column to a heavy media separating device,
the pump provided between the pulping column output and the heavy
media separating device input.
13. The method of claim 12, wherein the measuring step comprises
the step of measuring the specific gravity of the slurry containing
the sized raw mineral and media downstream of the pump and upstream
of the heavy media separating device; and the adding step comprises
the step of adding water to the sized raw mineral and slurry
mixture upstream of the pump and downstream of the pulping column
output.
14. The method of claim 10, where the mineral comprises coal, and
wherein the media comprises magnetite and/or ferrosilicon.
15. The method of claim 10, wherein the pulping column is
integrally formed with discharge chutework of the deslime screen,
such that the sized raw mineral from the deslime screen feeds
directly to the pulping column.
16. The method of claim 10, wherein the pulping column is
integrally formed with a drain section of the underpan of at least
one of the refuse screen and the clean mineral screen, such that
the slurry of media and water from the drain section is fed
directly to the pulping column.
17. The method of claim 10, wherein the pulping column is
integrally formed with both discharge chutework of the deslime
screen and a drain section of the underpan of at least one of the
refuse screen and the clean mineral screen, such that the sized raw
mineral from the deslime screen and the slurry of media and water
from the drain section is fed directly to the pulping column for
mixing.
18. A method of mixing raw mineral feed particles and a slurry of
media and water, said method comprising the steps of: providing a
pulping column integrally formed with discharge chutework of a
deslime screen, such that the sized raw mineral from the deslime
screen is received directly into the pulping column; receiving at
the pulping column a slurry of media and water directly from an
underpan of at least one of a refuse screen and a clean mineral
screen; mixing the sized raw mineral and slurry in the pulping
column according to a select proportion; and maintaining the slurry
of media and water in the mixture of sized raw mineral and slurry
at a select specific gravity.
19. The method of claim 18, wherein the maintaining step comprises
the steps of: measuring the specific gravity of the slurry
conataining media, water and sized raw mineral; and selectively
adding water to the mixture in response to the measured specific
gravity of the slurry to maintain the slurry at the select specific
gravity.
20. The method of claim 18, wherein the pulping column is
additionally integrally formed with a drain section of the underpan
of at least one of the refuse screen and the clean mineral screen,
such that the slurry of media and water from the drain section is
received directly into the pulping column.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed generally toward coal
preparation plants and, more particularly, toward an improved
integrally formed heavy media pulping column for mixing raw coal
particles with a slurry of media and water.
BACKGROUND OF THE INVENTION
[0002] Coal preparation plants separate organic and non-organic
solid particles by their specific gravities. The coal preparation
plant receives a feed of raw mined coal, and separates the raw
mined coal into clean coal and refuse. These plants typically
utilize two basic processing methods for separating raw coal from
rock and varying proportions of striated rock and coal from the
higher quality coal. The two processing methods include heavy media
and water based separation methods. Heavy media, utilizing a slurry
of media, e.g., water and magnetite or ferrosilicon, to separate
the coal from the refuse according to their specific gravity of dry
solids, is the most common separation process for larger size (Plus
1 mm-0.5 mm) particles. Whereas, water based separation processes
are more commonly used for the "cleaning" of the finer sized
particles, as that term is commonly understood in the coal
processing art. One type of heavy media circuitry used in the coal
preparation plants includes a heavy media cyclone.
[0003] Coal preparation plants using heavy media cyclones operate
with three separate types of screens for coal processing, namely, a
deslime screen, a refuse screen and a clean coal screen. A common
screening assembly used in many coal preparation plants today is
known as a vibratory banana screen. The deslime screen receives the
raw coal feed particles and separates them into coarse and fine
sized fractions. The coarse or larger sized particles discharged
from the deslime screen surface are directed to the heavy media
separation section of the coal preparation plant, while the finer
sized particles passing through the deslime screen are directed
toward the water based separation section of the coal preparation
plant.
[0004] The clean coal and refuse screens receive the clean coal and
refuse particles, respectively produced by the heavy media
separating section. While on the clean coal and refuse screens, the
clean coal and refuse particles are rinsed with water, and the
finer particles and water passing through the respective screens
are recirculated through the coal preparation plant. Rinsing the
clean coal and refuse particles is primarily done to recover the
particles of media, such as magnetite, remaining thereon as a
result of the coal/refuse separation process, as magnetite can be
quite expensive.
[0005] Traditionally, the majority of the media recovered by the
clean coal and refuse screens is recovered as a slurry of media and
water in the drain section of the underpan for each of the clean
coal and refuse screens. This media is mixed with sized raw coal
discharged from the deslime screen, piped to a pulping column and
pumped from the pulping column to the heavy media separation
section of the coal preparation plant.
[0006] The mixing of raw coal and media using conventional pulping
columns requires the inclusion of the heavy media sump for the
retention of media overflowing from the pulping column upon the
addition of the raw coal feed. As raw coal is added to the pulping
column, the displacement of media with raw coal increases the level
in the pulping column forcing the displaced media into the heavy
media sump. Conventional pulping columns may include an overflow
which reports to a separate heavy media sump. The displaced media
is then pumped back into the system. Alternately, conventional
pulping columns may be integral to the heavy media sump to collect
the overflow. These systems increase the overall size of the plant
footprint, and add to the cost of building the coal preparation
plant.
[0007] The present invention is directed toward overcoming one or
more of the above-mentioned problems.
SUMMARY OF THE INVENTION
[0008] In a coal preparation plant which receives a raw coal feed
and separates the raw coal feed into clean coal and refuse, an
apparatus is provided for use therein. The inventive apparatus
mixes the raw coal feed particles with a slurry of media and water
used for separating the raw coal feed into the clean coal and
refuse, without the requirement of an overflow for media storage.
The inventive apparatus includes a pulping column with an inlet
receiving both sized raw coal directly from a deslime screen, and a
slurry of media and water directly from an drain portion of an
underpan of at least one of a refuse screen and clean coal screen,
and an outlet by which the mixture of sized raw coal and slurry
exits the column. The pulping column mixes the sized raw coal and
the slurry of media and water according to a select proportion, and
it is then pumped to a heavy media separation section of the coal
preparation plant.
[0009] In one form of the inventive apparatus, the pulping column
is integrally formed with discharge chutework of the deslime
screen, such that the sized raw coal from the deslime screen feeds
directly into the pulping column. In a preferred form, the pulping
column is also integrally formed with a drain section of the
underpan of at least one of the refuse and clean coal screens, such
that the slurry of media and water from the drain section feeds
directly into the pulping column.
[0010] The pulping column may be either circular or rectangular in
design, and is sized so that there is no overflow of media upon the
addition of the raw coal feed and also to maintain the required
pump section head for pumping the mixture to the heavy media
separation section.
[0011] A nuclear density gauge may be provided for measuring the
specific gravity of the mixture output by the pulping column. The
nuclear density gauge is part of a control system that adjusts the
addition of water to the output mixture to maintain the output
mixture at a select specific gravity. Specifically, a water source
is connected to the pulping column via at least one valve. The
control valve adds water from the water source to the output
mixture based upon the measured specific gravity value.
[0012] In another form, the inventive apparatus includes a pump for
pumping the pulping column output mixture to a heavy media
separating device. The pump has a suction connected to the pulping
column output and an output connected to an input of the heavy
media separating device. The water source is preferably connected
between the pulping column output and the pump suction, while the
nuclear density gauge is preferably provided between the pump
output and the heavy media separating device input.
[0013] A method of mixing raw coal feed particles and a slurry of
media and water is also provided. The method generally includes the
steps of receiving at a pulping column, (a) sized raw coal directly
from a deslime screen, and (b) a slurry of media and water directly
from an underpan of at least one of a refuse screen and a clean
coal screen, and mixing the raw coal and slurry in the pulping
column according to a select proportion having a select specific
gravity.
[0014] In one form, the inventive method further includes the steps
of measuring the specific gravity of the sized raw coal and slurry
mixture output of the pulping column, and adding water to the
mixture in response to the measured specific gravity of the mixture
to maintain the mixture at the select specific gravity.
[0015] A pump may be provided for pumping the sized raw coal and
slurry mixture from the pulping column to a heavy media separating
device. The pump is generally provided between the pulping column
output and the heavy media separating device input. In a preferred
form, the specific gravity of the sized raw coal and slurry mixture
is measured downstream of the pump and upstream of the heavy media
separating device. The water is preferably added to the sized raw
coal and slurry mixture downstream of the pump and upstream of the
pulping column output.
[0016] In another form of the inventive method, the pulping column
is integrally formed with discharge chutework of the deslime
screen, such that the sized raw coal from the deslime screen feeds
directly into the pulping column.
[0017] In a further form of the inventive method, the pulping
column is also integrally formed with a drain section of the
underpan of at least one of the refuse and clean coal screens, such
that the slurry of media and water from the drain section feeds
directly into the pulping column.
[0018] It is an object of the present invention to:
[0019] remove the need for a heavy media sump in coal preparation
plants;
[0020] provide an apparatus for mixing the raw coal particles and
the slurry of media and water occupying minimal space in a coal
preparation plant;
[0021] provide a pulping column for mixing raw coal and a slurry of
media and water while minimizing pipe work and equipment costs;
and
[0022] to eliminate the overflow normally associated with mixing
sized raw coal and a slurry of media and water.
[0023] Other objects, aspects and advantageous of present invention
can be obtained from a study of the specification, the drawings,
and the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] FIG. 1 is a side view of a pulping column according to the
present invention in association with deslime, refuse and clean
coal screens in a coal preparation plant;
[0025] FIG. 2 is a combination top view and block diagram of the
pulping column according to the present invention associated with
deslime, refuse and clean coal screens in a coal preparation plant;
and
[0026] FIG. 3 is a combination top view and block diagram of a
pulping column according to an additional embodiment of the present
invention in association with deslime, refuse and clean coal
screens in a coal preparation plant.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Referring to FIGS. 1 and 2, a pulping column according to
the present invention is shown at 10 in association with a deslime
screen 12 in a coal preparation plant, shown generally at 14. The
deslime screen 12 receives a feed of raw coal 16 which is to be
processed by the coal preparation plant 14. The deslime screen 12,
with the addition of water, separates the raw coal 16 into coarse
and fine sized fractions. The deslime screen 12 includes screens 18
and 20 which size the coarse or larger raw coal particles from the
finer particles, with the finer particles and water passing to an
underpan 22 of the deslime screen 12.
[0028] The raw coal particles 16 screened by the deslime screen 12
are received directly at a coal inlet 24 of the pulping column 10.
The pulping column 10 is integrally formed with discharge chutework
25 of the deslime screen 12, such that the raw coal particles 16
from the deslime screen 12 feed directly to the pulping column 10.
These raw coal particles 16 are mixed with a slurry of media and
water in the pulping column 10, as will be hereinafter described,
and fed, via a pump 26, to a conventional heavy media separating
device 28 to produce clean coal 30 and refuse 32. Typically, these
coal processing techniques will utilize a media, such as magnetite,
and water to separate the clean coal particles 30 from the refuse
particles 32 according to their specific gravities.
[0029] The clean coal particles 30 are fed to a clean coal screen
34 and, similarly, the refuse particles 32 are fed to a refuse
screen 36. The clean coal particles 30 screened by the clean coal
screen 34 are passed to a conventional clean coal handling section
(not shown) of the coal preparation plant 14, while the refuse
particles 32 screened by the refuse screen 36 are passed to a
conventional refuse handling section (not shown) of the coal
preparation plant 14.
[0030] Since magnetite is typically utilized as the media by heavy
media separating device 28 for separating the clean coal 30 and
refuse 32 particles, each will include particles of magnetite
thereon. Since magnetite is generally expensive, rinsing the
particles on the clean coal 34 and refuse 36 screens is done
primarily to recover the magnetite particles adhering thereon for
recirculation through and/or further processing by the coal
preparation plant 14.
[0031] As shown more particularly in FIG. 2, the deslime 12, clean
coal 34 and refuse 36 screens are formed as one screen assembly 37
with partition members 38 partitioning the screen assembly 37 into
the various deslime 12, clean coal 34 and refuse 36 screens. The
clean coal 34 and refuse 36 screens include an underpan, shown more
particularly at 40 in FIG. 1, for receiving the recirculating media
water used to rinse the coal and refuse particles of any magnetite
adhering thereon, the washed-off magnetite, and any solid coal and
refuse particles that have broken to be finer than the respective
screen aperture openings. The underpan 40 is divided into a drain
section 42 and a rinse section 44. The majority of the magnetite
will be removed from the refuse and coal particles in the drain
section 42. Magnetite that has not passed through the clean coal 34
or refuse 36 screens to the drain section 42 will be rinsed off of
the respective clean coal/refuse particles and received in the
rinse section 44.
[0032] Referring to FIGS. 1 and 2, the drain section 42 includes a
conduit 46 connecting the drain section 42 to the pulping column
10, such that the drain section 42 can be considered as integrally
formed with the pulping column 10. Thus, the slurry of media and
water received in the drain section 42 will be directly received by
the pulping column 10 at a media inlet 47, as shown more
particularly in FIG. 1. For convenience, the chutework for the
underpan 22 of the deslime screen 12 has been omitted in FIG. 1 to
allow viewing of the underpan 40 associated with the clean coal 34
and refuse 36 screens.
[0033] The pulping column 10 mixes the raw coal particles 16 from
the deslime screen 12 and the slurry of media and water from the
drain section 42 of the underpan 40 according to a select
proportion. Typically, the select proportion is four parts by
volume of media and water to one part of coal. However, other
volumetric proportions may be utilized without departing from the
spirit and scope of the present invention.
[0034] Since the pulping column 10 is integrally formed with the
chutework of both the deslime screen 12 and the drain sections 42
of the underpan 40, there is no overflow from the pulping column
10. As the pulping column 10 becomes filled, any excess mixture of
coal and slurry will flow up the chute 46 to the drain section 42
of the underpan 40. The drain section 42 of the underpan 40 is
accurately sized to meet the return media requirements of the
system. The pulping column 10 is typically either circular or
rectangular in cross-section, and has a column height sufficient to
maintain the required pump suction head. Design of the inventive
pulping column 10 in this manner eliminates the need for a heavy
media sump for the retention of the media typically overflowing
from the pulping column upon the addition of the raw coal feed
particles, and also for the retention of the slurry of water and
media from the clean coal and refuse screens. Thus, the overall
size of the coal preparation plant area can be reduced.
[0035] The pulping column 10 includes an output 48 connected to a
suction 50 of the pump 26. The pump 26 has a discharge output 52
connected to an input 54 of the heavy media separating device 28,
and pumps the mixture of raw coal and slurry mixed in the pulping
column 10 to the heavy media separating device 28 for separation
into the clean coal 30 and refuse 32.
[0036] The specific gravity of the mixture of raw coal and slurry
will depend upon the ratio of media to water in the mixture. To
help maintain a select specific gravity of the mixture, which is
required for the desired separation of coal from refuse in the
heavy media separating device 28, a nuclear density gauge 56 is
provided to measure the specific gravity of the mixture. The
nuclear density gauge 56 helps maintain a select specific gravity
of the mixture for proper separation by the addition of water to
the mixture from a water source 58. The nuclear density gauge 56,
via control circuitry 60, controls valves 62 which are connected to
the water source 58 to add water to the mixture output by the
pulping column 10 in accordance with the measured specific gravity
valve. For example, if the specific gravity value measured by the
nuclear density gauge 56 is too high, the valves 62 will open to
allow the addition of water from the water source 58 to lower the
specific gravity of the mixture. In a preferred form, the water
from the water source 58 is added to the mixture at an area of the
mixture flow downstream of the pulping column outlet 48 and
upstream of the pump suction head 50. Also, in a preferred form,
the nuclear density gauge 56 is positioned to measure the specific
gravity of the mixture at an area of the mixture flow downstream of
the pump outlet 52 and upstream of the heavy media separating
device input 54.
[0037] FIG. 3 illustrates an additional embodiment of the pulping
column of the present invention, shown generally at 10', with like
elements of FIGS. 1 and 2 indicated with the same reference number
and elements requiring modification indicated with a prime (').
Basically, in the embodiment shown in FIG. 3, instead of the
deslime 12, clean coal 34 and refuse 36 screens being formed as one
screen assembly 37 as shown in FIG. 2, the deslime 12', clean coal
34' and refuse 36' screens are formed as three separate screen
assemblies, as shown in FIG. 3. The deslime screen 12' receives the
raw coal feed 16 and separates the raw coal feed 16 into coarse and
fine sized fractions. The coarse raw coal particles 16 screened by
the screens of the deslime screen 12' are received at the coal
inlet 24' of the pulping column 10' and fed directly to the pulping
column 10'. The clean coal 34' and refuse 36' screens receive the
clean coal 30 and refuse 32 particles, respectively, and rinse and
screen the respective particles in the same manner as previously
described. However, as the screens 34' and 36' are formed from
different screen assemblies, each includes its own underpan divided
into respective drain and rinse sections.
[0038] The underpan of the clean coal screen 34' includes a drain
section 64 and a rinse section 66. Most of the magnetite will be
removed from the clean coal particles 30 in the drain section 64.
Any magnetite that has not passed through the clean coal screen 34'
to the drain section 64, the water used to rinse the solid coal
particles of any magnetite adhering thereon, and any solid clean
coal particles that have broken to be finer than the clean coal
screen 34' aperture openings, will be received in the rinse section
66. The drain section 64 is appropriately sized and connected to
the pulping column 10, via a conduit 68, such that the slurry of
magnetite and water received in the drain section 64 is passed
directly to the pulping column 11' for mixing with the raw coal
particles 16 from the deslime screen 12'. In this manner, the drain
section 64 can be considered as integrally formed with the pulping
column 10'.
[0039] Similarly, the underpan of the refuse screen 36' is divided
into a drain section 70 and a rinse section 72. Most of the
magnetite will be removed from the refuse particles 32 in the drain
section 70. Any magnetite that has not passed through the refuse
screen 36' to the drain section 70, the water used to rinse the
solid refuse particles of any magnetite adhering thereon, and any
solid refuse particles that have broken to be finer than the refuse
screen 36' aperture openings, will be received in the rinse section
72. The slurry of media and water collected in the drain section 70
of the refuse screen 36' is passed directly to the pulping column
10' via a conduit 74. In this manner, the pulping column 10' can be
considered as integrally formed with the drain section 70. Again,
there is no overflow of any materials from the pulping column 10'.
As the pulping column 10' becomes filled, the water, magnetite and
coal and refuse particles will simply flow up the conduits 68 and
74 and into the respective drain sections 64 and 70 of the clean
coal 34' and refuse 36' screens.
[0040] The present invention provides a distinct advantage in that
a heavy media sump is not required in the coal preparation plant
14, 14'. This aids in reducing the overall plant area. Further,
since the pulping column 10, 10' does not include an overflow, no
additional sumps are necessary to catch this overflow. The slurry
of media and water and the sized raw coal particles are received
directly by the pulping column 10, 10', where they are mixed and
pumped to the heavy media separation device 28. While not
specifically shown in the drawings, typically a portion of the
slurry of media and water received in the drain sections of the
clean coal and refuse screens are bled out of the slurry flow and
passed to a dilute media sump (not shown) for further processing by
the coal preparation plant 14, 14'.
[0041] While the present invention has been described with
particular reference to the drawings, it should be understood that
various modifications could be made without departing from the
spirit and scope of the present invention. For instance, while the
inventive integrally formed heavy media pulping column 10, 10' has
been shown and described herein as used in a coal preparation plant
14, 14', the inventive integrally formed heavy media pulping column
10, 10' may be utilized in preparation plants for ore and minerals
other than coal, using separation media other than magnetite,
without departing from the spirit and scope of the present
invention.
* * * * *